The 3-Way Classic Part 8.

A quick build update. First up the passive filters. Building a set of Troels speakers calls for a set of filters Gravesen style don't you think? Not as complex with fewer and not so fancy components. Probably not as good but hopefully good enough. I try to put my money where it matters the most. And since the speakers are mirrored why not build mirrored filters?

I fastened the filters behind the mid-range chamber with extra tough Velcro. One option could be to bypass the 0.82 Ohms series resistor on the tweeter for some extra sparkle if the treble is found lacking.

Next up was the active filters. I had a hard time sourcing 180nF capacitors from my local supplier. I therefor had to recalculate the shelving low-pass filter based on 150nF instead. This is the final schema I used.

Note: the idea behind this circuit was good but I suspect it has serious flaws. Read this post for my final solution. Material below kept as a reference.

And this is the layout of the single layer board I etched.

I used 8P DIP sockets for the op-amps since I haven't decided what op-amps to use yet. I think I will use a set of NJM2068DD or NE5532P (or a mixture of them both) since I got a bunch of them laying around (and they perform great for the price). The jumpers are closed on the picture for unity gain but can be opened for some extra boost if bass is found lacking.

This marks the end of the eighth part about my 3-Way Classics. It also pretty much marks the end of the build apart from listening impressions. But before that I have to finalize the active filter with a power supply etc. Hmmmm - why not build a combined active filter and four channel power amp in the same style as my latest preamp...